Cloning cannot improve the genetic pool of the dog breeds as it makes an exact copy with the same genetic information. Breeding will give rise to genetic variations and diversity which helps the dog breed to survive and adapt to different situations in the environment hence improving the dog breeds.

Pros: 1) alleviate famine problem
2) there will be more nutrients included in the gm corn

Cons: 1) Public opinion of gm food may not be good
2) gm corn may contain unknown side effects caused by the combination of gene manipulation

Yes, we would accept it. If we don’t accept it, the people may die of starvation and this will in turn cause numerous problems to occur, be it politically, socially or economically.

a. C6(H2O)6

b. Refer to hardcopy for the drawing.

c. They should have different sweetness. They have different structures and functional groups, hence, they will react differently with the receptor of the tongue and lead to different level of sweetness.

Everything is related to chemical. All nutrients in food are chemical compounds. In other words, there is nothing in this world that can be “chemical-free”.

Acetone dissolves the polymer, allowing the gas of the foaming agent to escape. The polymer collapses on itself and is more dense because the gas has been removed.

a) LDPE cannot be used in this application because it does not have the required strength as strength of HDPE is greater than LDPE.
b) The molecules of HDPE must line up in a way that produces the required strength. Using a thin liner of HDPE allows sufficient flexibility.

When you try to stretch a piece of plastic bag, the strip nip arrows and “necks down”.
– Molecules align parallel to each other and in the direction of the pull.
– This alteration of the 3D structure is not reversible, if the pulling continues, the plastic breaks.

When same force is applied on a piece of paper, the paper tears rather than stretch.
– Cellulose molecules in paper are held more rigidly in place, and are not free to become aligned.

a) 1) Must be sufficiently strong until surrounding tissue has healed
2) Does not invoke inflammatory or toxic response
3) To be metabolised in the body after fufililing its purpose, leaving no trace
4) Must demonstrate acceptable shelf life and be easily sterilised

b) Contact lenses are made from poly(methylmethacrylate) (PMMA), silicon-based polymers, polyacrylamide and similar polymers.
Properties that are desireable in these materials:
1) transparent
2) flexibility
3) Low density
4) unreactivity to chemicals on the eye surface
5) tough
6) easy to manufacture
7) raw materials is in abundance
8) easy to mould
9) suitable refractive index
10) hydrophilic
11) allows oxygen gas pass through to the eye surface
12) produces lenses that are easy to insert, remove, clean and store

c) Hard lenses are made from PMMA
Soft lenses are made from polyacrylamide and silicon-based polymers
Polyacrylamide contains nitrogen atoms, when the polyacrylamide chains are cross-linked, the material absorbs water which keeps the lens soft and flexible and more easy to wear.
PMMA does not contain nitrogen atoms. They are hard and rigid which makes it less comfortable to wear since the lenses do not allow oxygen to pass directly to the cornea.

1. Different carbon atoms can differ in the number of neutrons (e.g. C-12 and C-14). They are termed as isotopes.
2. Different carbon atoms can differ in the number of electrons; different charges

Carbon vs uranium atoms

1. Isotopes of carbon are stable whereas isotopes of uranium are radioactive.
2. Carbon atoms have much less protons, neutrons and protons as compared to uranium atoms.
3. They have different atomic masses.

14N consists of 7 protons and 7 neutrons while 15N consists of 7 protons and 8 neutrons.
They have similar chemical properties and reactivity.

A. There are 94 protons in the nucleus of (239/94)plutonium

B. 93 protons – Neptunium
94 protons – Plutonium

C. The nuclei of radon-222 contain 86 protons.

A: Control rod assembly
B: Cooling water out of the core
C: Control rods
D. Cooling water into the core
E. Fuel rods